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Cocaine addiction vax trial offers some hope to users

An experimental vaccine designed to combat cocaine addiction demonstrated some promising results in a small human trial. Scientists in Texas say that the vaccine triggers the production of antibodies that bind to drug molecules, making them too big to enter the brain. But the trial was hardly an unqualified success.

About four out of every 10 volunteers that received all five doses of the vaccine experienced a buildup of the antibodies and half of that lot markedly reduced their use of cocaine compared to the placebo group. But about a quarter of the vaccine group failed to develop an appreciable amount of antibodies, leading the study's lead investigator to remark that more work remains to be done to develop an ideal jab. It also spurred some speculation that the resistant subjects may have been smoking crack.

Researchers said that they also observed another drawback. The vaccine reduced the euphoric effect associated with the drug, but didn't stop addicts from craving the drug. That led them to believe that the vaccine would not work for someone with a fully developed addiction. A much bigger study scheduled for early next year will enroll about 300 addicts to further test the vaccine's usefulness.

"Vaccines are one of our top priorities," says Dr. Nora Volkow, director of the National Institute on Drug Abuse, which is financing the clinical trials.